Mobilized Electrospray Device for On-Tissue Chemical Derivatization in MALDI-MS Imaging

Abstract

Applying solutions of a matrix or derivatization agent via microdroplets is a common sample preparation technique for matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) experiments. Mobilized nebulizer sprayers are commonly used to create a homogeneous matrix or reagent layer across large surfaces. Electrospray devices have also been used to produce microdroplets for the same purpose but are rarely used for large tissues due to their immobility. Herein, we present a movable electrospray device that can be used for large tissue sample preparation through a simple modification to an automatic commercial nebulizer device. As demonstrated for on-tissue chemical derivatization (OTCD) with Girard's reagent T using a mimetic tissue model, the sprayer has the additional benefit of being able to investigate reaction acceleration in OTCD when comparing electrostatically charged spray to electrostatically neutral spray. Finally, MALDI-MSI of fatty aldehydes is successfully demonstrated in rat brain tissues using this device for both OTCD and matrix application.

Mass spectrometry imaging of Arabidopsis thaliana with in vivo D2O labeling

“…All samples were dried in a vacuum (~400 mTorr) for 75 min. An in-house ESI sprayer (Paulson et al, 2023) was attached to a TM sprayer nozzle (HTX Technologies, Chapel Hill, NC, USA) and used for spraying colloidal silver as a matrix after 4:1 dilution (v/v) with methanol. The distance was kept at 3 cm between the tip of the ESI sprayer and the sample plate.…”